I recently started brewing kombucha and in one of my 7 day old jars I have a 1/4 inch scoby growing. I slid a straw down the edge to taste and then the scoby sank to bottom and is still sunk after a day. It's a bit too sweet. My last batch tasted just right at 9 days, but that batch was left undisturbed. I'm wondering if this current batch is slowed down now since the scoby isn't getting oxygen? So at 9 days it won't be like the previous batch?Will the drink still ferment with no growth on the top?

Yes it will still work without the SCOBY on the surface. You'll notice a new one will start to form.
If you want, you can take your straw and attempt to float the SCOBY by lightly blowing bubbles under it.

Another scoby quickly grew on top, must be a good sign. I can still taste the sugar , does this mean the beneficial properties arn't there yet? It does reek like vinegar and stings the throat.
Interesting because another batch I decanted yesterday has no sugar taste and less of a bite, was ready in 7 days. Started that one with a larger scoby in a 2 gal jar, whereas the sugary one was started with starter fluid only in a much smaller jar.
Might've answered one of my questions right there. So many variables at play with this stuff, I like it!

The yeast process the sugar; the bacteria produce acetic acid which makes the vinegar taste. If your batch is vinegary and sweet then it is most likely out of balance. You need to slow the bacteria and kick the yeast up a notch.